The present invention relates to electrochemical conversion cells, commonly referred to as fuel cells, which produce electrical energy by processing first and second reactants. For example, electrical energy can be generated in a fuel cell through the reduction of an oxygen-containing gas and the oxidation of a hydrogenous gas. The voltage provided by a single cell unit is typically too small for useful application so it is common to arrange a plurality of cells in a conductively coupled “stack” to increase the electrical output of the electrochemical conversion assembly.
For the purpose of describing the context of the present invention, it is noted that the general configuration and operation of fuel cells and fuel cell stacks is beyond the scope of the present invention. Rather, the present invention is directed to particular end unit configurations for fuel cell stacks and to general concepts regarding end unit design. Regarding the general configuration and operation of fuel cells and fuel cell stacks, applicants refer to the vast collection of teachings covering the manner in which fuel cell “stacks” and the various components of the stack are configured. For example, a plurality of U.S. patents and published applications relate directly to fuel cell configurations and corresponding methods of operation. More specifically, FIGS. 1 and 2 of U.S. Patent Application Pub. No. 2005/0058864, and the accompanying text, present a detailed illustration of the components of a fuel cell stack. Further, U.S. Pat. App. Pub. Nos. 2004/0137299 and 2004/0229100 also present detailed descriptions of the structure of a fuel cell stack. The respective disclosures of these publications are incorporated herein by reference, to the extent they relate to the general structure of a fuel cell stack.